[LLVMdev] undefined reference to 'llvm_gcda_start_file', 'llvm_gcda_emit_arcs', etc

Alexey Samsonov
Fri, 15 Mar 2013 06:51:03 -0000

On Fri, Mar 15, 2013 at 1:36 AM, Qun Fa <testforqunfa at gmail.com> wrote:

> Hi All,
>
> I think Nick's suggestion is correct, my code was linked against
> libprofile_rt.a, which had gcda profiling code before, but was removed
>
https://github.com/llvm-mirror/llvm/commit/218042a02305a3cc38d968a97ff9ecf4b4abe6ff
>
> So, I couldn't find the correct symbols from libprofile_rt.a any more.
>
> Now my assumption is I need to use the correct library that is provided by
> compiler-rt. May I know which one?
>
> I am building the entire llvm/clang including compiler-rt based on the
> instructions given on the clang get started page (
> http://clang.llvm.org/get_started.html), but with CMake instead of
> Makefile. But I also noticed in the compiler-rt/lib/CMakeLists.txt file, we
> have the following FIXME.
>
> # FIXME: Add support for the profile library.
>
> So, if I want to use the correct library, do I have to switch to Makefile?
> Any ideas?
>

Yeah, can you try Makefile (I think it should build libprofile_rt from
GCDAProfiling.c that you need). I'll see if I can add CMake support for
profile in compiler-rt any time soon.
However, looks like Clang driver won't be smart enough to link two archives
(lib/libprofile_rt.a and the one under lib/clang/3.3/linux/...), so we may
need to patch the driver as well.


>
> Thanks very much,
> Qun
>
>
>
> On Thu, Mar 14, 2013 at 8:46 AM, Qun Fa <testforqunfa at gmail.com>
wrote:
>
>> Thanks for your reply.
>>
>> May I know which is the recommended library that should be linked
against?
>>
>> I am currently linking libprofile_rt.a.
>>
>> And I have noticed the differences that, if we do
>>
>> `nm libprofile_rt.a | grep llvm`
>>
>> with my old copy of the llvm/clang installation, I can see
>>
>> 00000000000005e0 T _llvm_gcda_emit_arcs
>> 0000000000000b48 S _llvm_gcda_emit_arcs.eh
>> 0000000000000430 T _llvm_gcda_emit_function
>> 0000000000000aa8 S _llvm_gcda_emit_function.eh
>> 00000000000006c0 T _llvm_gcda_end_file
>> 0000000000000b98 S _llvm_gcda_end_file.eh
>> 00000000000003d0 T _llvm_gcda_increment_indirect_counter
>> 0000000000000a80 S _llvm_gcda_increment_indirect_counter.eh
>> 0000000000000000 T _llvm_gcda_start_file
>> 0000000000000a08 S _llvm_gcda_start_file.eh
>>
>> They are the symbols that my test build is looking for.
>>
>> But with the latest codebase, here is what I saw
>>
>> 00000000000000a8 T llvm_start_basic_block_tracing
>> 0000000000000067 T llvm_trace_basic_block
>> 0000000000000467 T llvm_decrement_path_count
>> 000000000000042a T llvm_increment_path_count
>> 0000000000000662 T llvm_start_path_profiling
>> 0000000000000020 T llvm_start_edge_profiling
>> 0000000000000020 T llvm_start_opt_edge_profiling
>>
>> Thanks again,
>> Qun
>>
>> On Thu, Mar 14, 2013 at 1:11 AM, Nick Lewycky <nicholas at
mxc.ca> wrote:
>>
>>> Qun Fa wrote:
>>>
>>>> Hi,
>>>> I am trying to test my project and get the code coverage with a
version
>>>> of clang compiler that was built from the latest llvm/clang
codebase.
>>>>
>>>> It worked for a while. But today, after I updated my local
checkout, and
>>>> re-build llvm, clang and compiler-rt, when I test my project
again, I
>>>> got the errors with undefined reference to
'llvm_gcda_start_file',
>>>> 'llvm_gcda_emit_arcs',
'llvm_gcda_emit_function', and
>>>> 'llvm_gcda_end_file'.
>>>>
>>>> I have searched the codebase, and have found the functions are
defined
>>>> in GCDAProfiling.c file, but not sure why this suddenly
doesn't work
>>>> for me.
>>>>
>>>> Anyone can give any suggestions?
>>>>
>>>
>>> Those symbols should be provided by
compiler-rt/lib/profile/**GCDAProfiling.c.
>>> There used to be a copy in llvm's tree, but I deleted that one
recently.
>>> It's possible you used to be using the one from llvm, but now
need to
>>> switch to using the one from compiler-rt?
>>>
>>> Nick
>>>
>>>
>>
>
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>


--
Alexey Samsonov, MSK
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